In the related art, as technologies for detecting the position of a moving object such as a pedestrian, technologies for using the GPS (Global Positioning System), using a wireless device, and using a position change obtained from autonomous navigation (dead reckoning) have been known. Among these, the technology for using a wireless device is a technology for detecting the position of a pedestrian according to a communication state between a wireless device disposed in an arbitrary place and a terminal device carried by the pedestrian.
In the technology for using the GPS or a wireless device, an absolute position can be detected. However, since there is a problem that a measurement error occurs or the technology may not be used in a place at which a radio wave does not arrive, a position may not continuously be detected with high accuracy. Accordingly, there is a technology for estimating a more exact position by combining an absolute position and a position change calculated from autonomous navigation. Further, in some navigation devices, a technology called a map matching for correcting an estimated position using map information is utilized.
However, in the conventional technologies, there is a problem that it is difficult to specify the position of a pedestrian with high accuracy. Specifically, an absolute position may not continuously be detected with high accuracy in some cases, as described above. Further, since errors are accumulated over time in the autonomous navigation, it is difficult to continuously detect a position with high accuracy only using the autonomous navigation. Further, in regard to the map matching, a huge amount of effort is required to prepare a map indicating places where pedestrians can walk. That is, in a map indicating places where pedestrians can walk, places where pedestrians can walk are present more than places in which vehicles can travel, and it is considered that the places are frequently changed. Therefore, a huge amount of effort is required to make preparations. As a result, in the conventional technologies, the position of a pedestrian may not be specified at low cost, with ease, and with high accuracy.